AppendDedup

A top-level write_mode=append_dedup (not a policy).

1. Checks the dedup key(s) against existing rows on the sheet
2. New keys are appended; existing keys are skipped (not a full row update like SoftRefresh)
3. For Meta / Google / TikTok / FB / IG — an incremental window (~3 days) on top of the dedup, based on dedup_refresh_date_field

Compatible with scheduling.

When to use it

When you need uniqueness of entities (campaign/ad id) across repeated runs of overlapping ranges.

Related

• write-modes
• append